The invention relates to a method for operating a drive device of a motor vehicle, which has at least one electric machine with a phase angle detector and a drive shaft that can be operatively connected with the electric machine. The invention also relates to a drive device.
The method serves for operating the drive device of the motor vehicle. Hereby the drive device for example provides a torque that is directed towards driving the motor vehicle, in particular towards accelerating or decelerating the motor vehicle. The drive device includes the electric machine. Hereby it can be provided that the drive device only include the electric machine and is insofar configured as electric drive device. As an alternative of course beside the electric machine the drive device can also include a further drive aggregate, in particular an internal combustion engine. In this case the drive device is configured as a hybrid drive devices. The output shaft can be operatively connected with the electric machine. For example the output shaft is permanently operatively connected with at least one axle or at least one wheel of the axle of the motor vehicle. For example the operative connection between the electric machine and the output shaft is established via at least one manual transmission and/or a shifting clutch.
The phase angle detector serves for detecting a phase position or a rotary angle position of the electric machine in particular of a rotor and/or a motor shaft of the electric machine. The phase angle can for example be used for controlling the electric machine in particular for commuting the electric machine. The phase angle detector can also be referred to as rotary encoder or rotary angle encoder. In particular it is configured as an angular position sensor preferably as incremental angular position sensor or absolute angle encoder. Of course also other configurations can be realized.
For example the phase angle detector is configured not to output a signal when the electric machine has a defined phase angle or one of multiple phase angles. Outside of the phase angle or the phase angles n the other hand the phase angle detector outputs a signal. Thus when a defect of the phase angle detector and/or a connecting line which connects the phase angle detector with a control device of the electric machine is present, it may be that no signal of the phase angle detector is recognized and insofar for example received by the control device that the defined rotation angle or one of the defined rotation angles is present.
However beside a defect the constant return value of the phase angle detector can also have other causes. For example the phase angle detector and/or its connection line may be defective. As an alternative it is also possible that the electric machine outputs a torque which is not sufficient however to move the moor vehicle. This is for example the case when the motor vehicle stands on a slope or an obstacle is present, for example a curb against which at least one of the wheels of the motor vehicle pushes. The latter can also occur due to a steering wheel angle when the motor vehicle stands next to a curb, i.e., the motor vehicle stands essentially parallel to the curb.